The overall goal is to understand the mechanisms by which prolactin release, synthesis and storage are controlled. The specific aims are: 1) To test if mechanisms controlling Ca+2-induced prolactin release fit into an overall pattern developed for Ca+2-mediated actions. This pattern is a rapid increase in cytosolic Ca+2 levels that quickly returns to basal, and sustained Ca+2 influx that does not increase cytosolic Ca+2 concentrations because efflux is also stimulated. We will see if estrogen and agents that affect cyclic AMP affect this pathway. 2) To test if proteins that are not normally packaged into secretory granules are when made in GHcells, and if the storage of these proteins is regulated as prolactin storage is. 3) To characterize proteins specifically related to secretory tissue whose synthesis is induced when prolactin storage is induced. 4) To determine if mRNAs induced in GH cells by estrogen concentrations lower than that required to induce prolactin show the same responses in normal cells and tumor cells. The techniques we will use are 45Ca++ influx, aequorin luminescence, measurements of cyclic AMP, transfection of GH cells with clones of genomic DNA, isolation of secretory granules, electron microscopy, differential hybridization and cloning into phage, and associated recombinant DNA technology.